You are correct. If you come across these, you can flag them for moderator attention rather than making meta posts as well.
For the big boned, I migrated it to biology. For the sense question, since it has a correct answer and is somewhat older, I elected to leave it on the site, since I don't think a better answer would be gotten on a different site. I am inquiring about the third.
If there is any question that you feel needs moderator intervention such as should be on another site, you can use the flag link under the question, select "In need of moderator intervention", and explain your reasoning. That's part of what the site needs, is strong users supplementing the efforts of the moderators. Cheers!